1. Field of the Invention
This invention relates generally to an apparatus for cutting an end portion of insulation surrounding a conductor of a wire segment and, if desired, stripping the insulation therefrom, and more specifically it relates to an apparatus in which the insulation on a plurality of wire segments, each having a different gauge conductor, can be completely cut around its entire periphery to permit subsequent stripping and use of the wire segment, for example, in multi-segment, multi-gauge wiring harnesses.
2. Description of the Prior Art
Prior art apparatus are known for feeding a wire strand along a path, cutting successive wire segments of desired length from the wire strand, cutting the insulation therefrom and, if desired, stripping the insulation and attaching wire terminals to one or both ends of the segments.
U.S. Pat. Nos. 4,713,880 issued Dec. 22, 1987 to Robert O. Dusel et al entitled "Lead Making Machine", and 4,653,160 issued Mar. 31, 1987 to Finn Thorkildsen et al entitled "Apparatus for Making Finished Wire Harness or Subassemblies Therefor", both assigned to the same assignee as the present application, are typical of this prior art. The prior art apparats may use wire stripper modules, such as Model CS-18 available from Artos Engineering, wherein a single pair of bypassing knives each having a V-shaped cutting profile are used to cut and strip insulation from the wire segment. The distance the knives bypass each other is programmable so that one set of knives can be used to cut the insulation on different gauge conductors. The use of V-shaped knives creates a diamond shaped cutting profile when the two knives overlap which cuts the insulation at only four points on the circumference of the segment wire thus always leaving some insulation uncut. These uncut portions must shear when the cut insulation portion (called a slug) is slid off the conductor. However, these uncut portions do not always easily shear and pulling can cause the entire wire segment to be pulled out of position, or cause the insulation remaining on the wire segment to be stretched to the extent it takes a set before it breaks resulting in an improper strip length. It is therefore preferable to use knives having a cutting profile with a semicircular notch sized to exactly fit the gauge of the conductor to be stripped so that two overlapping knives will completely cut the insulation around its entire circumference without cutting the conductor. The use of semicircular cutting profiles will avoid tearing and stretching of the insulation remaining on the wire segment as the insulation slug is slid off the conductor, but the disadvantage is that wire segments with only one gauge of conductor can be processed. To process a plurality of conductors of different gauges, a plurality of sets of knives each having a different size semicircular cutting profile must be used.
Thus, the problem is one of providing a mechanism that will quickly and efficiently permit shifting of the correctly sized set of knives to cut the insulation on a wire segment having one specific gauge conductor and to then be able to instantaneously select different sets of knives for cutting and stripping different gauge conductors which are subsequently presented at the same workstation so that groups of wire segments of different gauges are presented in a precise sequence for assembly into a wire harness. One prior art apparatus for using a plurality of sets of knives each having a different sized semicircular cutting profile is disclosed in U.S. patent application Ser. No. 238,590, filed on Aug. 31, 1988 by Kenneth A. Wollermann et al entitled "Apparatus for Cutting, Conveying and Programmably Stripping Wire Segments" and assigned to the same assignee as the present application. The apparatus in Ser. No. 238,590 mounts the plurality of sets of knives on an arcuate turret which in turn is mounted for horizontal back and forth reciprocation about an axis to place the proper set of knives at the workstation after which the knives are closed to cut the insulation which can then be stripped. While this apparatus performs very well, the pivotal reciprocation of the turret increases the size, complexity and cost of the cutting and stripping apparatus. It is desirable, therefore, to provide a wire stripping apparatus which will be simpler in design, smaller in size, have a reduced number of components and eliminate the need for the turret and associated driving and actuating mechanisms in order to reduce manufacturing costs, enable higher rate production speeds and achieve more efficient production.